Device for power transmission in a working machine

ABSTRACT

A device to transmit power from the power system of a working machine to one or more moving parts ( 25, 26 ) of a tool replaceably attachable to a first part of the working machine which is in the form of a beam, or such, comprising a first element ( 7 ) arranged on the working machine and driven by its power system, a second element ( 11 ) movably attached to the tool and means ( 8, 12 ) arranged to mechanically interconnect both of said elements so that a displacement of the first element via the working machine&#39;s power system brings about a movement of the second element on the tool.

FIELD OF THE INVENTION AND PRIOR ART

The present invention concerns a device to transmit power from the powersystem of a working machine to one or more moving parts of a toolreplaceably attachable on a first part of the working machine which isin the form of a beam or such.

The working machine can be of any type and trucks, front loaders,digging machines and demolition machines can be mentioned as examples,which are generally supplied with different types of tools. The term“tool” also includes so-called working instruments, and examples of whatis here intended to be thought of as tools are forks of different types,scoops, man-baskets, lever arms and other special equipment for handlingspecial loads.

In order to illustrate the invention but without limiting the invention,the case of a tool in the form of a fork unit can be briefly described.Such a fork unit is used for the handling of pallets and other suchgoods. The fork unit is usually expected to have different functionswhich require some kind of driving, i.e. the unit has to be suppliedwith power (energy). Examples of such functions are that the forks couldbe driven apart or moved together depending on what kind of load is tobe handled or that they could be laterally moved relative to a frame ofthe fork unit. The power required to carry out these functions isobtained by the fork unit from the working machine's power systemaccording to known devices of the type defined in the introduction,usually a hydraulic system, since this device has components to rapidlyinterconnect the working machine's hydraulic system with a hydrauliccylinder arranged on the tool to carry out said functions.

This means that when a change of the tool on the working machine isdesired the driver has to get out of the driver's cabin and manuallyinterconnect said components for interconnection of the truck'shydraulic system with one or more hydraulic cylinders on the tool. Thiscan be troublesome for the driver, and he can therefore sometimes betempted to neglect to change the tool if this is not absolutelynecessary and instead use an unsuitable tool. This can in its turnresult in the risk of injury.

Another disadvantage with such known devices and this way ofinterconnecting the working machines hydraulic system with hydrauliccylinders on the tool lies in the fact that there are no such connectioncomponents that are completely protected against impurities in thehydraulic oil. This constitutes a decreasing operation safety factor asthe use of proportional valves in hydraulic systems increases.

SUMMARY OF THE INVENTION

The aim of the present invention is to provide a device of the typedefined in the introduction, which makes it possible to at least partlyremedy the above-mentioned inconveniences.

This aim is achieved according to the invention by providing such adevice, that comprises a first element arranged on the working machineand driven by its power system, a second element movably attached to thetool and means arranged to mechanically interconnect both of saidelements so that a displacement of the first element via the workingmachine's power system brings about a movement of the second element onthe tool.

By mechanically interconnecting the working machine's power system withthe tool in this way the above-mentioned impurities in the hydraulicliquid, or such, of the working machine's power system can be totallyeliminated. Therefore in the case of a pressure medium system, such as ahydraulic system, as the power system of the working machine, thepressure medium will not be exposed to the surroundings in any way bytransfer to pressure medium cylinders of the tool via openable rapidconnection components. The working machine's hydraulic system cantherefore be held entirely closed relative to the external environment.

Another advantage with the inventive device is that by using amechanical power transmission between the working machine and the toolit offers the possibility to achieve an automatic connection of theworking machine's power system to the tool on testing the tool in saidfirst part of the working machine, so that in the case where theattachment itself is of the rapid attachment type the driver does nothave to get out of the driver's cabin to change the tool, so that a toolchange will be considered to be simple and the risk of the driveromitting to change the tool will therefore be significantly reduced. Adevice according to a preferred embodiment of the invention providesthis possibility in that said means for mechanical interconnection arearranged to automatically establish a mechanical interconnection of thefirst and second elements on attachment of the tool to the workingmachine's first part.

According to another preferred embodiment of the invention, whichconstitutes a development of the previous embodiment, the means formechanical interconnection comprise engagement means on the first andsecond element, which are arranged to co-operate with one another toautomatically move into power-transmitting engagement with one anotheron attachment of the tool to said first part. By using such engagementmeans, that can for example be made of a projection of one element and arecess arranged to receive the projection on the other, the mechanicalinterconnection can be simply realised on moving the tool and said firstpart together.

“Recess” should be understood to have a broad meaning and includes everytype of indentation, or such, that can form a power-transmitting seatingfor a projection, for example such as a U-formed cradle arranged toreceive a projection between the sides of the U so that power can thenbe transmitted between these sides and the projection. This type ofrecess makes the establishment of the mechanical interconnection verysimple without requiring high precision work.

According to another preferred embodiment of the invention said secondelement is arranged to operate a drive unit to set parts of the toolinto motion relative to a body of the tool on displacement of the secondelement relative to the body of the tool, and the second element isconnected to a second pressure medium cylinder on the tool, which lacksa power supply through any pressure medium source, to cause movement ofthe piston of this second cylinder relative to a casing of the cylinderby movement of the first element. In this way a drive unit that workswith pressure medium is provided on the tool and works in the same wayas if the working machine's pressure medium system were directlyconnected thereto, despite the fact that both systems will be totallyseparated from each other as regards the communication of pressuremedium.

It is thereby therefore possible, and even the subject of a furtherpreferred embodiment of the invention, that the second pressure mediumcylinder is arranged to function as a pump to drive one or moreadditional pressure medium cylinders arranged on the tool, which are inpressure medium flow communication with the second cylinder. The pumpcan for example hereby power a cylinder for the respective fork of atool in the form of a fork unit to move the forks relative to a body ofthe tool. Both of the additional pressure medium cylinders can therebyadvantageously have internally interconnected pressure medium chambersto make a movement of one of the forks dependent on a movement of theother fork, so that via movement of the first element, and thereby thesecond element, both of the forks can either move in oppositedirections, apart or together, or in the same direction for lateraldisplacement relative to a body of the tool.

Further advantages as well as advantageous features of the inventionwill be apparent from the following description and the other dependentclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

A preferred embodiment of the invention is described below as an examplewith reference to the attached drawings, in which:

FIG. 1 very schematically illustrates a conventional working machinewith examples of some instruments, on which an inventive powertransmission device could be applied,

FIG. 2 is a perspective view, which illustrates how an interconnectionbetween a working machine and a tool takes place in a device accordingto a preferred embodiment of the invention,

FIG. 3 is a perspective view of part of the inventive device ininterconnected position,

FIG. 4 is a perspective view of the inventive device applied on a forkunit, where bulky parts of the working machine have been left out, and

FIG. 5 is a simplified sketch illustrating the principle function of thedevice in FIG. 4.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

FIG. 1 illustrates a working machine 1 in the form of a front loader aswell as some of a number of different possible tools and instrumentsthat could be attached to the machine's arms 2 and obtain power from theworking machine's power system via an inventive device. A fork unit 3, ascoop 4 and a clamping unit 5 are shown here.

A device according to a preferred embodiment of the invention fortransmitting power from a power system, of such a working machine to oneor more moving parts of a tool replaceably attachable on a first part,such as the arm 2 or a beam, of the working machine, will now bedescribed with simultaneous reference to FIGS. 2-4.

The device has a first element 7 arranged on the end of the workingmachine's first part and which can be driven into motion along a track 6by the working machine's power system. This element is provided with arecess 8 in the form of an upwardly open U-shaped cradle. In order toachieve this movement the device comprises a pressure medium cylinder 9arranged on said first part near an attachment arrangement for the tool,and connected to the working machine's power system. The first element 7is connected to the hydraulic cylinder's piston rod and is movabletransversely in the direction of attachment of the tool on the arm via aschematically indicated attachment device 10, which will not bedescribed in more detail.

The device additionally has a second element 11 movably arranged on thetool with a rod-like projection 12 arranged thereupon so that onattachment of the tool to the working machine it is in such an initialposition that it is automatically “docked” in the cradle's recess 8which is driven upwards from below onto the projection. Mechanicalinterconnection is in this way established by the first element with thesecond, so that a movement of the first element 7 results in acorresponding movement of the second element on the tool.

Reference is now made to FIG. 5. The second element 11 is connected to asecond pressure medium cylinder 13 by being fixedly attached to itscylinder wall and arranged to provide movement of a piston of thiscylinder relative to the casing 31 by moving the casing relative to apiston rod that goes through the casing. This second hydraulic cylinderis arranged to function as a pump to drive one or more additionalpressure medium cylinders 16, 17, which are in pressure medium flowcommunication with the second cylinder, more particularly so that one ofthe cylinders 16 has a chamber 18 connected with a chamber 19 of thesecond cylinder 13 via connection 34 and the second chamber 20 isconnected with a chamber 21 of the cylinder 17 via connection 33. Thepump cylinder 13 will hereby on movement of its piston 14 relative tothe casing cause movement of the piston 22, 23, in both of theadditional cylinders 16, 17. Each additional cylinder is arranged tofunction between points on a frame 24 of the tool and a fork 25, 26 thatis desplaceably recieved in the frame's transverse direction.

The function of the inventive device that has just been described aboveis the following: when the hydraulic pump 27 of the working machine'shydraulic system 28 is powered to move the piston of the device'shydraulic cylinder 9, the first element 7 will then be displaced andthereby even displace the second element 11. We assume now that thehydraulic cylinder's 9 piston moves to the right in FIG. 5. This meansthat the casing of hydraulic cylinder 13 is displaced to the rightrelative to the piston 14 and hydraulic liquid is thereby pumped fromthe chamber 19 into the hydraulic cylinder's 16 chamber 18 to displacethe fork 26 to the right. This means that hydraulic liquid issimultaneously transmitted from cylinder 16 to the chamber 21 of thecylinder 17, so that the piston 23 and thereby the fork 25 are displacedto the left. Hydraulic liquid, that is thereby squeezed out of thecylinder's 17 chamber 29, will be conveyed into the chamber 31 of thepump cylinder via the connection conduit 32. Consequently both forkswill move apart. If the movement of the driving cylinder 9 is reversed,the forks 25, 26 will move towards each other.

Instead of having the connection 33 between the chamber 20 of thecylinder 16 and the chamber 21 of the cylinder 17 and the connection 34between the pump cylinder's chamber 19 and the cylinder's 16 chamber 18,these connections could be modified so that the forks 25, 26 wouldinstead always be displaced in the same direction for lateraldisplacement of the forks.

The invention is of course not in any way limited to the preferredembodiment described above, but a number of modification possibilitiesshould be apparent for a person skilled in the art, without that personhaving to deviate from the basic idea of the invention as defined in theattached claims.

For example a male-type interconnecting means could well be arranged onthe first element and a female-type interconnecting means could bearranged on the second element.

“To mechanically interconnect” as used above and in the attached claimsshould be interpreted as if there is a mechanical connection betweenboth elements so that a movement of one of the elements automaticallyresults in the movement of the other. However it would be possible toprovide mechanical interconnection by using “non-mechanical” means, suchas a permanent magnet on the first element arranged to be forced towardsa piece of suitable material on the second element to lock theserelative to one another. The definition used covers such cases.

Other types of movement rather than the straight-line movement that hasbeen illustrated above are of course possible to achieve with aninventive device. For example the first element could cause a gear wheelor such on the tool to rotate via a mechanical connecting means. Evenother movement patterns would be possible.

1. Device to transmit power from a power system (28) of a workingmachine (1) to one or more moving parts (25, 26) of a tool (3-5)replaceably attachable to a first part of the working machine which isin the form of a beam, or such, wherein it comprises a first element (7)arranged on the working machine and driven by its power system, a secondelement (11) movably attached to the tool and means (8, 12) arranged tomechanically interconnect both of said elements so that a displacementof the first element via the working machine's power system brings abouta movement of the second element on the tool.
 2. Device according toclaim 1, wherein said means (8, 12) for mechanical interconnection isarranged to automatically establish a mechanical interconnection of thefirst (7) and second (11) elements on attachment of the tool to theworking machine's first part.
 3. Device according to claim 2, whereinthe means for mechanical interconnection comprise engagement means (8,12) on the first and second elements, which are arranged to co-operatewith each other to automatically establish power-transmitting engagementwith each another on attachment of the tool to said first part. 4.Device according to claim 3, wherein one of the engagement means isformed from a projection (12) arranged on the first element and theother engagement means is formed from a recess (8) arranged on thesecond element and arranged to receive the projection on moving the tooland the first part together.
 5. Device according to claim 2, wherein thesecond element (11) is displaceably arranged in a track on the tool viapower transmission from the first element (7).
 6. Device according toclaim 1 wherein it comprises an arrangement (13, 16, 17) forinterconnection of the second element (11) with said moving parts (25,26) of the tool to transmit a movement of the second element to amovement of these tool parts.
 7. Device according to claim 1, wherein itcomprises a pressure medium cylinder (9) arranged on said first part ofthe working machine near an attachment arrangement for the tool, andconnected to the working machine's power system (28), and said firstelement (7) is formed from, or connected to, a part of said cylinderthat is moveably arranged relative to the first part.
 8. Deviceaccording to claim 7, wherein the first element (7) is formed from anend of a piston rod of the cylinder which is distant from the piston. 9.Device according to claim 7, wherein the pressure medium cylinder (9) isa hydraulic cylinder connected to the working machine's power system(28) that is in the form of a hydraulic system.
 10. Device according toclaim 1 wherein said second element (11) is arranged to operate a driveunit to set parts (25, 26) of the tool into motion relative to a body(24) of the tool on displacement of the second element relative to thebody of the tool.
 11. Device according to claim 10, wherein said secondelement (11) is connected to a second pressure medium cylinder (13) onthe tool, which lacks a power supply through any pressure medium sourceto cause movement of the piston (14) of this second cylinder relative toa casing of the cylinder by movement of the first element (7). 12.Device according to claim 11, wherein the second pressure mediumcylinder (13) is arranged to function as a pump to drive one or moreadditional pressure medium cylinders (16, 17) arranged on the tool,which are in pressure medium flow communication with the secondcylinder.
 13. Device according to claim 6, wherein the tool is a forkunit with forks (25, 26) that are laterally displaceable along a frame(24), and the interconnection arrangement is arranged to transmit amovement of the second element (11) to a movement of the forks. 14.Device according to claim 12, wherein it comprises two said additionalpressure medium cylinders (16, 17) for driving a fork (25, 26) each. 15.Device according to claim 14, wherein both of said additional pressuremedium cylinders (16, 17) have mutually interconnected pressure mediumchambers to make a movement of one fork (25) dependent on a movement ofthe other fork (26).
 16. Device according to claim 15, wherein saidadditional pressure medium cylinders (16, 17) are interconnected tocause a displacement of the forks (25, 26) in opposite directions forseparating or bringing them together relative to each other via movementof the second element (11).
 17. Device according to claim 15, whereinboth of said additional pressure medium cylinders (16, 17) areinterconnected to cause a displacement of the forks (25, 26) in the samedirection for simultaneous displacement thereof to one side or the otherof a body of the tool via movement of the second element
 11. 18. Deviceaccording to claim 3, wherein the second element (11) is displaceablyarranged in a track on the tool via power transmission from the firstelement (7).
 19. Device according to claim 4, wherein the second element(11) is displaceably arranged in a track on the tool via powertransmission from the first element (7).
 20. Device according to claim19, wherein it comprises an arrangement (13, 16, 17) for interconnectionof the second element (11) with said moving parts (25, 26) of the toolto transmit a movement of the second element to a movement of these toolparts.